The present invention relates to a one-way clutch unit which is convenient if used for connection and disconnection of power between, for example, an automobile engine and an air conditioner as well as a one-way clutch therefor.
Conventionally, as a power transmission device used for connection and disconnection of power between an automobile engine and an air conditioner, there is a device in which an electromagnetic clutch is provided between a pulley and a rotating shaft that drives a compressor. The electromagnetic clutch is turned on while the engine is rotating so that a rotational power is transmitted to the rotating shaft from the pulley. On the other hand, the electromagnetic clutch is turned off when the engine is stopped to disconnect the rotating shaft from the pulley, so that the rotating shaft is driven to rotate by a motor.
However, the conventional power transmission device requires an electromagnetic clutch and a control part that controls on-off action of the electromagnetic clutch. This makes the structure of the power transmission device complicated and increases the device size.